US3450355A - Ore crusher - Google Patents

Description

June 17, 1969 w P Y 3,450,355

ORE CRUSHER Fi led Aug. 5, 1966 Sheet of 2 F/'g./ I

i j I Eugene W Murphy 1N l ENTOR.

June 17, 1969 Filed Aug. 5, 1966 E. W. MURPHY ORE CRUSHER Sheet g 012 Eugene W. Murphy INVENTOR.

United States Patent 3,450,355 ORE CRUSHER Eugene W. Murphy, Rte. 1, Box 123, Brownsville, Oreg. 97327 Filed Aug. 5, 1966, Ser. No. 570,615 Int. Cl. B02c 2/06, 23/02 US. Cl. 241--46 9 Claims ABSTRACT OF THE DISCLOSURE This invention generally appertains to improvements in pulverizing and crushing devices and more particularly relates to novel improvements in devices for crushing or pulverizing ore and similar matter to desired degrees of fineness.

The present invention specifically constitutes improvements over pulverizing, crushing and grinding devices designed primarily for crushing and pulverizing ores. Devices of such type are generally classified as gyratory crushers in that they comprise a heavy pestle or grinding ball having an obliquely arranged axis and rotated with a gyratory action in a subjacent grinding chamber or urn by a power driven crank arm. Some of the primary drawbacks of such known devices reside in the fact that they require the use of an additional classifying means, whereby the pulverized ore is classified so as to separate the finished pulverized particles, of the desired size, from larger size particles. Further, with such additional classifying means, it is necessary to collect the unfinished ore particles and return them to the pulverizing and crushing device for further treatment. This necessitates additional equipment and constitutes a time-consuming operation.

In addition, with such known types of devices, there is no means provided for controlling the inflow of the ore to be ground into the grinding chamber or urn and, consequently, the problem of clogging of the device is present, as well as the fact that proper pulverizing or crushing action, within a limited amount of time, is not achieved.

Accordingly, an important object of the present invention is to provide an ore crusher or pulverizer, which overcomes the drawbacks of known devices, in that means is provided and is structually associated with the crusher to function as a classifier, whereby, in structural association with an outlet means for the crusher, classifying means is provided for permitting the discharge of the particles, which are of the desired size, and for returning the oversized particles back to the crusher or pulverizer for further crushing action, until the material is crushed to the desired particle size.

Another important object of the present invention is to provide means, which is automatically responsive to the movements of the pestle in the grinding chamber for the intermittent, controlled admission of ore, which is to be pulverized, into the chamber. In this fashion, controlled amounts of ore to be treated are admitted into the grinding chamber at regular, spaced intervals, whereby the pestle can operate, in coaction with the interior of the grinding chamber, so as to achieve speedier and more eflicient grinding results.

Another object of the present invention is to provide means which enables the water in the grinding chamber to discharge all of the ground or pulverized ore from the chamber, under the swirling movements of the water reactive to the physical bodily movements of the pestle in the grinding chamber.

Another important object of the present invention is to provide a crusher or grinder, for ore or other material, which will require less power than conventional machines and which can be controlled, in its operation, so that it can operate, under slow or fast operating conditions, depending upon factors, such as ore size, desired pulverization, and the nature and quantity of the ore deposited into the grinding chamber.

An important feature of the present invention resides in the provision of means whereby the crushed particles are classified by specific gravity, in that the particles suspended in the water are carried by the water, as the water is given an upward swirling action created by the movements of the pestle in the grinding chamber, and the water and particles are conveyed through an outlet means, which functions as a classifier, in that the particles of the desired fineness are carried off with the water, while the heavier particles gravitate back down into the grinding chamber for further grinding treatment.

Another important feature of the present invention resides in the provision of a movable and controlled outlet means for an ore storage hopper or container, such means being intermittently opened to release a determined quantity of the ore to be pulverized into the grinding chamber and such means being automatically controlled and operated by the movements of the pestle or grinding member in the grinding chamber or urn. Thus, the pestle controls the admission of the ore to be pulverized through a structural connection means between the pestle and the ore hopper or container.

Another important object of the present invention is to provide a compact, simply and elliciently constructed and easily and automatically operated ore crusher or pulverizer which is operable at variable speeds and at little expense.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIGURE 1 is a top plan view of a crusher or pulverizer constructed in accordance with the present invention;

FIGURE 2 is a vertical cross-sectional view taken substantially on line 2--2 of FIGURE 1;

FIGURE 3 is a fragmentary, detailed elevational View, partly in section, of the means for controlling the automatic admission of ore into the grinding or pulverizing chamber, responsive to the rotation of the pestle in the grinding chamber;

FIGURE 4 is a vertical sectional view, taken substantially on line 4-4 of FIGURE 3;

FIGURE 5 is a horizontal, cross-sectional view taken substantially on line 55 of FIGURE 3, and

FIGURE 6 is a fragmentary horizontal cross-sectional view taken substantially on line 6-6 of FIGURE 2.

Referring now more particularly to the accompanying drawings, the ore crusher or pulverizing device 10 includes a supporting framework 12, which is composed of an open rectangular top section 14 and a solid, rectangular base section 16. The base section supports the top frame section 14 by means of vertically disposed angle irons 18, which are positioned at the corners of the base 16 and the top section 14 and the angle irons or vertical connecting legs 18 serve as supports for structural adjuncts of the crusher or pulverizer, as will be described.

Apart from the supporting framework 12, which may actually be of any desired construction, provided the same is essentially composed of interconnected and vertically spaced top and bottom sections and side portions, which may serve as the interconnection means, the crusher or pulverizer essentially comprises a vertically positioned, annular body member 20, which is provided internally, at its lower end, with a liner bowl or urn 22. The liner bowl 22 and the interior of the body portion 20 define a grinding chamber 24 and an outflow chamber 26, respectively.

The tubular body portion 20 has its lower edge 28 seated on a resilient, annular support 30, which is interposed between the lower edge 28 and a mounting block 32. The mounting block 32 is fixedly superimposed on the base 16 by fasteners 34 and the annular body portion 20 is fastened to the block and seated on the resilient cushioning support 30 by means of fasteners 36, which are secured to the block and toan apertured outstanding annular flange 38, which is carried by a ring 40 that is fixedly circumposed on the lower end portion of the body portion 20.

The grinding bowl 22 is disposed in the lower end of the end portion of the annular body portion 20 and has its base 42 seated in a circular recess 44 provided in the upper face of the mounting block 32, with the annular wall 46 of the bowl serving as a liner for the lower end portion of the inside of the annular body portion 20. The inner surface of the base 42 of the bowl 22 cooperates with a pestle or grinding cone 48, as does the inner surface of the annular side wall 46 of the bowl. Thus, the bowl defines a grinding chamber 24, which is subjacent the chamber 26, which is constituted by the interior of the upper end portion of the body portion 20.

The pestle or grinding cone 48 has its axis obliquely arranged in the grinding chamber 24 and is formed with a semispherical replaceable bottom surface 50, which cooperates with the inner surface of the base 42 of the bowl. The pestle has an annular side wall 52, which cooperates with the inner surface of the side wall 46 of the bowl.

The pestle 48 is formed with an axial bore 54 which receives an operating shaft 56, the lower end 58 of the operating'shaft being countersunk in a counterbore 50 of the bore 54 and serving to hold the replaceable bottom 50 of the pestle in place. The pestle is locked on the shaft or rod by a suitable locknut 62.

The rod 56 extends obliquely upwardly through the open upper end of the body portion 20 and has its upper end portion carried by an operating crank arm 62, which is substantially horizontally disposed. The crank arm is formed with an opening 64. The opening 64 is provided with a bearing sleeve 66 through which the upper end portion of the operating rod or shaft 56 extends. The bearing sleeve 66 is formed on its underside with a flange 68, which cooperates with a flange 70 formed on a collar 72 that is circumposed on the shaft and is fixed, as by setscrews, in adjustable positions along the axis of the shaft. A compression spring 74 is coiled around the rod 56 and bears between the flanges 68 and 72 and serves to urge the pestle or grinding cone 48 downwardly into the grinding chamber 24, so that the base or undersurface of the pestle firmly engages the upper surface of the base 42 of the grinding bowl 22.

In lieu of the spring-urged arrangement, it is contemplated that a hydraulic or some such similar means may be provided for serving the purpose of holding the pestle or grinding cone 48 under pressure in proper orientation, for grinding and crushing purposes, within the grinding chamber 24.

The crank arm 62 is formed as a part of an operating shaft 76, which is provided, adjacent its upper end, with a pulley 78 that is engaged by a driving belt 80, the belt being entrained over a driving pulley 82, which is operated by a suitable prime mover (not shown). The lower end of the shaft 76 is supported by a bearing assembly 84, which is carried by brace bars 86 that are horizontally disposed and fixed, in interconnected relation, with the legs or standards 18. Similarly, the upper end of the shaft 86 is rotatably supported by a bearing assembly 88, which is carried by brace bars 90, in a fashion similar to the arrangement of the brace bars 86.

It can thus be seen that the crank arm 62 will rotate the pestle 48, which has a gyratory action in the bowl 22, the pestle or grinding cone 48 functioning within the chamber 24 and the ore material being crushed between the side walls 52 of the pestle or grinding cone 48 and the inner surface of the side wall 48 of the bowl, in the initial crushing or pulverizing action. Then, the material is crushed still finer at the bottom 42 of the bowl, with the material being crushed to a fine state by the inner sweeping coaction between the undersurface of the replaceable base or bottom section 50 of the pestle and the upper surface of the base 42 of the bowl.

An inlet conduit 92 is supported in a downwardly and inwardly inclined position by a support means 94, which is in the form of a bracket means that is carried by the framework 12 and the inner discharge end of the conduit 92, overlies a funnel 96, so that water from the conduit 92 pours into the funnel 96. The funnel 96 is of conical shape and, adjacent its lower apex end, is formed with a side wall opening 98, with which a conduit 100 communicates. The conduit 100 is inserted within a downwardly and inwardly sloped side opening 102, at its lower end, the opening being formed through the wall of the annular housing or body portion 20, immediately above the grinding chamber 24. The conduit 100 is braced by a collar 104, which is circumposed thereon, and which is attached by a strap 106 to the annular body portion 20. Thus, water, from a suitable supply source, enters the funnel 96 at its open major end by virtue of the inlet conduit 92 and passes into the grinding chamber 24 through the conduit 100. Control means, in the nature of valve means (not shown) may be provided for controlling the flow of water through the inlet conduit 92, under certain operating conditions of the crusher, as will be described.

A hopper 108 is disposed above the funnel 96 and has a lower outlet end 110, which is adapted to communicate with the funnel 96 for the delivery of matter, such as ore M, from the hopper to the funnel 96 and from the funnel, through the conduit 100, where it is carried along with the infiowing water, into the grinding chamber 94. The hopper 108 is supported by the brace bars, which form the brace assembly 86, through the arrangement of attaching straps 112, as shown in FIGURE 1, and the hopper is also supported by a brace bar 114, which extends transversely between opposing corner standards or angle irons, as can be appreciated from a consideration of FIGURE 2. A feed inlet tube 116 is in constant, free communication with an opening 118 formed in the upper end wall of the hopper, so that the hopper is constantly filled with ore or other material M, the material entering the hopper through the tube 116, which is connected to a suitable source and which is fed in a suitable means (not shown).

Means is provided whereby the ore M is intermittently admitted into the funnel 96 and whereby a controlled and measured amount of ore is admitted, at such times, so that, at regular, intermittent intervals, during the operation of the pestle, a quantity of ore enters the grinding chamber through the conduit 100 with the ore being admixed in the funnel 96 and conduit 100 with the constantly infiowing water from the Water inlet conduit 92. Such means comprises a closure member 120 for the discharge end of the hopper 108.

As shown more particularly in FIGURES 3 and 4, the closure member is in the form of a spout and has opposing side walls 122 and a bottom wall, which is formed with an inner fiat, horizontal end portion 124, that actually serves as a closure for the outlet 110- and a downwardly and outwardly sloped forward portion 126, which cooperates with the opposing spaced side walls to form the spout, when the member is in an inclined position, as shown in FIGURE 2. When the member is closed, the flat end portion 124 of the bottom wall securely closes off the opening 110 of the hopper, as can be seen in FIG- URE 3.

The closure member 120 is mounted for pivotal movement from a closed position, as shown in FIGURE 3, to an open position, as shown in FIGURE 2. The pivotal mounting means includes lugs 128, which project transversely in aligned fashion outwardly from the opposing side walls of the hopper and protrude therebeyond and pass through suitable openings in the opposing side walls 120 of the closure member, as shown in FIGURE 4. Any other suitable pivot means may be provided, whereby the closure member may be moved from open to closed positions, relative to the lower discharge end 110 of the hopper 108.

The operation of the closure member 120 is controlled, as aforestated, by the rotary movements of the pestle 52 and its supporting rod or shaft 56. Thus, as shown in FIGURES 3 and 4, the side walls 122 have depending portions 122a and 122b, which depend below the bottom wall portion 124 and which support a transverse rod 130. The eyelet end 132 of an operating rod 134 is circumposed on the rod 130, with the rod 134 freely depending therefrom. Below the eyelet end 132, the rod 134 is formed with a collar 136, that is adjustable and is fixed in adjusted positions, along the axis of the rod, by a nut 138. Similarly, the lower free end portion 140 of the rod is exteriorly threaded and supports a collar or washer 142 that is held in adjusted positions, with respect to the axial extent of the rod, by means of a locknut assembly 144.

An actuating arm 146 is provided with an outer free end portion, which is formed with an aperture to receive the rod 134, with washers 149 being disposed on opposite sides of the horizontally disposed, flat end portion of the arm and being circurnposed on the rod. Alternately operating springs 148 and 150 are coiled around the rod and act in opposition to each other. Thus, the spring 150 is positioned between the washer on the upper end of the arm 146 and the collar 136 and the spring 148 is positioned between the washer on the underside of the arm 146 and the collar 142. The springs serve to counterbalance each other so that, in the normal position, as shown in FIGURE 3, the springs tend to hold the arm 146 in a substantially horizontal position, thereby ensuring that the opening 110 of the hopper 108 will be closed.

The arm is formed with an integral vertical end portion 152, which is pivotally mounted to upstanding ears 154 on the top edge 156 of the body portion by means of a pivot pin 158.

The end portion 152 is formed at its outer extremity with a lateral offset flange 160, which is provided with a suitable aperture to receive the shank of a bolt 162. The bolt 162 supports a spherical ball 164 on its outer end, the 'ball being formed with a suitable bore 166 for this purpose and having a counterbore 168 to receive the head 170 of the bolt, which is anchored to the flange by a nut 172.

The arm portion 152, which is pivoted, as at 158, for vertical movement and which carries the ball 164 on its outer end, is positioned on a resilient flange 174, which overlies the upper edge 156 of the body portion and has an annular binding or mounting portion 176 fixedly circumposed about the outer surface of the body portion, at the upper end edge 156 by a band 178. The resilient flange 174 supports the arm 152 and maintains it in a normal horizontal position, with the springs 148 and 156 in balanced relation, as shown in FIGURE 3, so that the closure or valve plate 124 for the hopper opening is shut or closed.

Means is provided and is carried by the operating rod or shaft 56 for the pestle or pulverizing cone 48 so as to actuate the arm, upon each full 360 movement of the rod within the body portion 20. Such means, as shown in FIG- URE 2, includes a semi-spherical cam plate 180, which is secured, in an encircling manner, on the rod or shaft 56 by means of a mounting collar 182, which is fixedly circumposed on the rod by any suitable fastening means, such as a radial setscrew.

Thus, as can be appreciated from a consideration of FIGURE 2, when the rod 56, as it makes its full 360 circular movement in the body portion 20, approaches the arm unit, the cam member 180 rides over the spherical ball 164 and forces the inner end portion 152 of the arm downwardly, the arm swinging about the pivot point 158. Such action causes the end portion 146 of the arm to move upwardly and this results in the downward swinging movement of the closure plate 124 from the discharge opening 110 of the hopper, so as to position the member in an inclined relation between the hopper and the funnel 96, as shown in FIGURE 2. For this short period of time, while the cam member is in engagement with the ball 164, the hopper is open so that the ore contents or other material M therein gravitates freely through the outlet 110 into the discharge spout 120 and into the funnel 96.- The ore is mixed in the funnel and the conduit 100 with the water, which is constantly inflowing through the conduit 92.

Therefore, it can be realized that the rod 56, in its bodily rotative movements, causes or produces an intermittent regular admission of a measured amount of ore into the grinding chamber 24. The quantity of ore, which is to be admitted, can be controlled by the dimensions of the cam 180 in relation to the ball 164, so as to hold the closure or valve plate 124 open for shorter or longer periods of time. Once the cam 180 rides past the ball 164, the rubber or resilient flange 174 and the counterbalancing action of the springs, causes the arm to return to its normal horizontal position, as shown in FIGURE 3, wherein the springs are in equilibrium on opposite sides of the arm portion 146 and maintain the valve or closure plate 124 shut so as to close olf the outlet 110 for the hopper.

The rotation of the pestle or grinding cone 48, through the crank arm 62, and the gyratory action, due to the obliquely arranged axis of the pestle and rod 56, in relation to the grinding chamber 24, causes the pestle 52 to rotate with a gyratory action in the bowl 22.

As aforestated, the ore is initially ground between the side wall 52 of the pestle and the inner surface of the annular side wall 46 of the bowl and then a final, finer grinding action is realized by the coaction between the undersurface of the base 50 of the pestle and the upper surface of the base 42 of the bowl.

The rotation of the pestle with a gyratory action produces or creates an upward swirling action of the water, as indicated by the arrows, the water being swirled upwardly to an outlet means 184, which comprises an outlet conduit 186 that is fixed in a suitable opening 188 in the side wall and extends downwardly and outwardly from the body portion 20 in communication with the upper chamber 26 thereof.

Means is provided and is structurally associated between the rod 56 and the body portion 20 so that the swirling water is confined in its upward, swirling movements to the outside area or zone of the chamber 26, adjacent the inner surface of the side wall thereof. This is particularly of importance during the initial starting action of the crusher. Such means includes an inwardly and downwardly slanted or sloping flange 190, which is disposed internally of the body portion 20 and is provided with an annular mounting flange 192, which mounting flange is suitably fixed on the inner side of the body portion 20, below the upper edge 156. The flange 190 is sloped downwardly and inwardly and has a lower annular edge 194. An annular plate 196 is circumposed on the rod 56 by means of an annular mounting collar 198. The annular plate 196 is fixed, by means of its mounting collar 198, so that it is disposed normal to the longitudinal axis of the rod 56, thereby disposing the plate 156 in an oblique arrangement, similar to the placement of the pestle. The plate underrides the edge 194 of the flange 190, as shown in FIGURE 6, and serves with the flange 190 to prevent any water from splashing out through the open upper end of the chamber 26, particularly during the starting movements of the pestle. After the pestle or pulverizing cone has been in operation, the water will be swirled upwardly immediately adjacent the inner surface of the wall of the body portion 20 in the upper chamber 26, so that the water, with the pulverized ore, as shown in FIGURE 2, is forced by the gyratory rotary movements of the pestle 48 in the grinding chamber 22 upwardly and outwardly through the outlet conduit 186.

Classifying means 200 is provided in structural and functional association with the outlet conduit 186 and comprises a receiver funnel 202, which has an apertured inner wall 204, with the outlet conduit 186 being fitted through the aperture in the wall 204 so as to discharge the water and ore held in suspension in the discharge water into the funnel 202. The opposing outer wall 206 of the funnel is inclined slightly, from a horizontal plane, and is provided, adjacent its upper end, with an opening to receive the inner end 208 of a discharge trough means 210 for the pulverized ore, which has been pulverized to a state, that is the intended state of fineness desired. The classifying means 200 includes a recirculation pipe 212, which is in communication with the outlet 214 between the walls 204 and 206 and which is at the bottom of the funnel. The recirculation pipe 212 has its lower end fitted in a downwardly inclined opening 214 formed in the body portion 20, immediately above the chamber 24, with the outlet for the recirculation conduit 212 and the outlet for the conduit 100 being disposed in substantially the same horizontal plane, and, at least, being disposed immediately above the chamber 24.

The pulverized ore discharge trough 210 is supported by suitable bracket means 216 carried by the framework and the recirculation pipe 212 is supported by suitable support means 218, which is attached to the framework.

In operation, water constantly flows into the grinding chamber 24 from the water inlet conduit 22, which is in communication with the funnel 96. The pestle 48 is placed in operation by rotating the actuating arm 62, through the belt drive from a prime mover or through any other suitable drive arrangement, so that the pestle sets up :a gyratory bodily rotational movement in the grinding chamber 24. A measured quantity of ore M is discharged from the hopper 108, upon each full rotative, bodily movement of the pestle 48, through the coacting means, which includes the cam on the pestle operating shaft or rod '56 and the actuating arm, having the ball engaged by the cam means, with the arm controlling the closed or opened positioning of the closure plate 124 for the outlet of the hopper. As the ore M discharges gravitationally into the funnel 96, it is admixed with the inflowing water and the water and are are carried by the conduit 100 into the grinding chamber 24. The material is thus fed into the side of the pestle 48 and is crushed on the inner side of the side of the bowl or um 22. The material is crushed still finer at the bottom of the bowl, as aforedescribed. Then, the crushed ore and water are swirled upwardly to the discharge conduit 186.

The finely crushed ore will skim off the top of the water in the funnel 206 and be discharged by the discharge trough 210, while the heavier or larger particles, which have not been ground to the desired or sufficient size, will, becau e of their weight, gravitate downwardly 8 into the recirculation conduit 212 and reenter the chamber 24 for further grinding treatment by the pestle.

Of course, the apparatus can be used without the classifying means 200 for a certain size material. This may be done by controlling the speed of the pestle and controlling the inflow of the water in the conduit or pipe 92.

It can be appreciated that the appartus will crush more material using less power and that the finished product will be crushed, classified and washed so that the finished pulverized material, irrespective of its nature, will be discharged from the discharge trough 210 in the desired state or condition.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. An ore crusher comprising a grinding chamber, a pestle operatively mounted in said grinding chamber and coacting with the walls of the grinding chamber for crushing ore introduced into the chamber, means for actuating the pestle for grinding action in the grinding chamber, means for introducing ore into the grinding chamber, means for conveying water into the grinding chamber, outlet means for the pulverized ore, and ore classifying means associated with said outlet means, said ore classifying means including means for the discharge of the ore in the desired pulverized size and recirculation means for returning larger sized particles back to the grinding chamber for further grinding action thereon by the pestle, said ore outlet means including conduit means disposed above the grinding chamber for conveying the discharging admixed water and ore, a bowl-like receptacle substantially horizontally disposed and with which the conduit means communicates for establishing a flowing body of water therein, the discharge means for the ore in the desired pulverized state including a downwardly inclined trough which is disposed at the level of the water in the bowl-like receptacle so that the smaller sized and lighter weight particles will skim off the top of the water in the receptacle and flow downwardly through the outlet means and said means for returning larger sized particles to the grinding chamber including a recirculation pipe in communication with the lower end of the bowl-like receptacle and in communication with the grinding chamber, whereby the heavier sized particles will gravitate through the body of water in the bowl-like receptacle and return through the recirculation pipe into the grinding chamber.

2. The invention of claim 1, wherein the inlet for the commonly entering ore and water and the inlet opening for the recirculation pipe are disposed immediately above the grinding chamber.

3. The invention of claim 2, wherein means is provided for preventing splashing out of the water and ore from the grinding chamber and ensuring the outflow of the water and ore, under the swirling action of the water, through the outlet means into the bowl-like receptacle.

4. The invention of claim 3, wherein said last named means includes a flange bafiie means overlying the outermost portions of the grinding chamber and means carried by the pestle actuating means in coactive complementary arrangement with the bafile means.

5. An ore crusher comprising a grinding chamber, a pestle operatively mounted in said grinding chamber and coacting with the walls of the grinding chamber for crushing ore introduced into the chamber, means for actuating the pestle for grinding action in the grinding chamber, means for introducing ore into the grinding chamber, means for conveying water into the grinding chamber and outlet means for the pulverized ore, said pestle being conical and having an annular side wall and a bottom semi-spherical replaceable surface forming element, said grinding chamber being constituted by a bowl having an annular side wall cooperating with the side wall of the pestle and a substantially flat bottom wall having an inner surface over which the bottom surface forming element moves, said pestle being disposed in an oblique position in the bowl.

6. The invention of claim 5, wherein said actuating means for the pestle includes a shaft obliquely arranged in the chamber and attached to and supporting the pestle, said shaft and pestle being axially arranged, means connected to the shaft for bodily rotating the shaft and rotating the pestle bodily in the bowl a full rotational 360.

7. The invention of claim 6, wherein means is provided for holding the pestle under pressure in the bowl.

8. The invention of claim 7, wherein means is provided and is actuated by the shaft for controlling the means for introducing ore into the bowl so that one is introduced in intermittent fashion.

9. The invention of claim 8, wherein classifying means is associated with the outlet means for the ore and includes means for returning ore of larger size than the desired particle size back to the bowl for further grinding action.

References Cited UNITED STATES PATENTS 281,511 7/1883 Howland 241-46 512,208 1/1 894 McCleery 241-212 X 559,980 5/1896 Kin Kead 241-202 931,316 8/1909 Kirksey 24146 1,009,004 11/ 1911 Willma 241202 1,219,408 3/1917 Hackstaff 61: a1. 241-46 X 1,485,618 3/1924 Kellogg 241-212 X 2,345,474 3/ 1944 Haverland 241-212 X 2,544,634 3/ 1951 Mitchell 241-202 WILLIAM S. LAWSON, Primary Examiner.

U.S. Cl. X.R.

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